JPH02216809A - Electric double-layer capacitor - Google Patents

Abstract

PURPOSE:To improve contact of interface between a collector electrode and a polarized electrode, etc., and reduce electric resistance at the interface by providing a halogenated polyolefin resin layer which is superb in adhesion properties and stable in both organic and water electrolytic solution between the collector electrode and the polarized electrode of at least paper shape and then by adhering them. CONSTITUTION:Collector electrodes 10 and 10' are constituted of a paper-shaped conductor containing at least a fiber-shaped conductive material and an organic combining material and the collector electrodes 10 and 10' and at least polarized electrodes 11 and 11' are adhered by a polyolefin resin halide (however, halogen indicates F, Cl, BR, and I) and a conductive halogenated polyolefin resin layers 13 and 13' containing a conductive material. In this case, it is desirable that the conductive halogenated polyolefin resin layers 13 and 13' should be provided when providing an electrode for outside connection to the collector electrodes 10 and 10' and a halide of polyolefin resin should be a main constituent for adhering an insulating material and the collector electrodes 10 and 10'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention particularly relates to an electric double layer capacitor with improved adhesiveness between a current collecting electrode and a polarizable electrode.

[Conventional technology]

Electric double layer capacitors have a capacitance per unit volume that is several thousand times higher than that of conventional capacitors, so they can have both a capacitor and a battery component, and are suitable for applications where the latter is preferred, for example. For example, it is used as a backup power source.

An electric double layer capacitor, for example, as shown in Fig. 6,
Gaskets 2 facing each other with a porous separator 1 in between.
2' is provided with a pair of polarizable electrodes 3.3', each of which has a layer made of activated carbon or the like impregnated with an electrolytic solution, and each polarizable electrode is made of a conductive rubber sheet such as conductive butyl rubber containing a carbon blank. It is known to have a structure in which an electron conductive current collecting electrode 4.4' is provided to constitute a basic cell, and this basic cell is sealed.

Incidentally, recent electronic devices are required to have high density and high performance due to their small size and light weight, and there is a strong demand for electric double layer capacitors that are components of these devices to be thin and large in capacity.

[Problem to be solved by the invention]

In response to these demands, as shown in Figure 6, a current collector electrode, a polarizable electrode, and a gas carrier are compressed, bonded, and sealed, and a conductive rubber sheet is attached to the current collector electrode. If the thickness of the conductive rubber sheet is made too thin, mechanical strength cannot be maintained, and making the sheet thinner has problems with reliability, and internal resistance cannot be reduced. There was a problem.

In addition, when the electrolyte of the polarizable electrode is an organic electrolyte, for example, an electrolyte consisting of tetraethylammonium and T-butyrolactone, the butyl rubber of the current collecting electrode used may swell or partially dissolve, causing the internal This creates a problem in that the resistance increases and the current that can be taken out is reduced.

The purpose of the present invention is to provide a current collector electrode that maintains mechanical strength even if it is thin, and not only have a strong adhesion between the current collector electrode and the polarizable electrode, but also provide a method in which the adhesive layer can be used for either organic or aqueous electrolysis. The object of the present invention is to obtain a thin, large-capacity electric double layer capacitor having a sealed structure that is chemically stable even with liquids.

[Means to solve the problem]

In order to solve the above problems, the present invention includes: a non-electronically conductive and ion-permeable porous separator; a polarizable electrode provided on at least one side of the porous separator;
In an electric double layer capacitor having a current collecting electrode bonded to both sides of the porous separator and polarizable electrode structure, and an insulating material bonded to the periphery of the current collecting electrode on both sides,
The current collecting electrode is made of a paper-like conductor containing at least a fibrous conductive substance and an organic binder, and the adhesion between the one-current electrode and at least the polarizable electrode is made of a halide of polyolefin resin (however, Halogen is F, Cj
! , Br, and I) and a conductive halogenated polyolefin resin layer containing a conductive substance.

It is preferable that the adhesive between the insulating material and the current collecting electrode be made of a halide of polyolefin resin as a main component.

Next, the present invention will be explained in detail.

The fibrous conductive substances used in the current collecting electrode of the paper-like material in the present invention include Aus Cu, copper group of Ag,
Pts Irx Ru,, platinum group metals such as Pd, Ni, F
Iron group such as e, stainless steel, A12-, Ta-Nb5
Single substance, alloy or mixture thereof belonging to various valve metals such as Ti1Zrs'A, Mo, 5n02,
Examples include single metal oxides or mixtures of metal oxides such as RuO2. Further, conductive polymers such as rayon, polyacrylonitrile, phenol, etc., carbonized or graphitized products such as fused polycyclic compounds such as coal tar pitch, polyaniline, and polythiophene may be mentioned. These may be used alone or in a mixture of two or more.

Among these, when an aqueous electrolyte such as sulfuric acid is used, metal materials are likely to corrode and generate gas, so it is preferable to use fibrous carbonized materials of non-metallic materials.

The above-mentioned conductive substance is bound by an organic binder, and examples of this organic binder include cellulose, polypropylene,
Polyamides such as 6 nylon, 6.6 nylon, 6° 10 nylon, polyester, polyethylene, polyolefins other than those mentioned above, fluororesins such as tetrafluoroethylene alone or copolymers with others, thermoplastic resins, or phenol,
Examples include single thermosetting resins such as epoxy and polyester, or mixtures thereof, modified products thereof, and natural fibers such as Manila hemp.

In order to bond the conductive substance with the organic binder, for example, the conductive substance is dispersed together with the organic binder in a solvent such as water, and this dispersion is made by, for example, a paper machine.
This may be further bonded under pressure to uniformly disperse the conductive substance in the organic binder. In this way, a paper-like current collecting electrode can be obtained. The pressure used to form this paper-like material may be applied not only at room temperature but also under heating.The thickness of the current collecting electrode of the paper-like material is preferably 5 to 200 .mu.m, particularly preferably 10 to 100 .mu.m.

Furthermore, in the present invention, the polarizable electrode contains at least activated carbon and an electrolyte, and optionally contains a conductive substance and a binder. The activated carbon, electrolyte, conductive substance, and binder are described in Japanese Patent Application Laid-open No. 190318/1983.
Examples include those described in Japanese Patent Application No. 62-209216.

Further, the insulating material in the present invention includes polypropylene resin,
It is made of a material that is stable in the electrolyte, such as polyethylene resin or halogenated polyolefin resin.

In the present invention, the current collecting electrode of the paper-like body and at least the polarizable electrode are bonded via a conductive halogenated polyolefin resin layer, and this conductive halogenated polyolefin resin layer is made of a polyolefin resin. Contains at least a halide and a conductive substance.

Examples of the halogenated polyolefin resin include halogenated polyolefin resins such as polypropylene, polyethylene, and ethylene-vinyl acetate copolymer. The halogens include F, CI, Br, I
At least one of the above is mentioned. The halogenation rate, that is, the proportion of halogen in the entire resin, is 1). 5 to 41% by weight. The halogenation rate is 1). If it is less than 5% by weight, it tends to become a solution, and if it is more than 41% by weight, the adhesiveness tends to be weak.

Furthermore, the conductive substance used in the conductive halogenated polyolefin resin layer is the same as the conductive substance described above and can be used regardless of its shape.

These may be used alone or in combination of two or more.

The solid composition ratio of the halide and the conductive substance in the polyolefin resin is 5 to 200% for the former to the latter.
% by weight is preferred, more preferably 10-150% by weight
It is.

In addition to the current collecting electrode, polarizable electrode, and insulating material, the electric double layer capacitor of the present invention uses a porous separator and, if necessary, an external connection electrode. Assembling the insulating material and the electrode for external connection is as follows: ■ Current collecting electrode and polarizable electrode on the paper sheet, ■ Current collecting electrode and insulating material on the paper sheet, ■ Current collecting electrode on the paper sheet and electrode for external connection. Of these, the conductive halogenated polyolefin resin layer may be used as the conductive halogenated polyolefin resin layer, but it may also be an adhesive layer containing no conductive substance or other adhesive layer. At least for (1), a conductive halogenated polyolefin resin layer is used as the adhesive layer, but for (2), this may be used, but other conductive adhesive layers may also be used.

To form a conductive halogenated polyolefin resin layer between the current collecting electrode, the polarizable electrode, the insulating material, and the external connection electrode, a conductive halogenated polyolefin resin layer is formed using a solution of a polyolefin resin halide dissolved in a solvent. The adhesive obtained by mixing the substances is applied to one or both of the parts of the polarizable electrode, current collecting electrode, insulating material, and external connection electrode to be adhered, preferably at room temperature to 90°C. A conductive adhesive layer may be formed by overlapping and adhering the polarizable electrode and the current collecting electrode in a fluid state before drying and solidifying, and then drying completely. A conductive adhesive layer may be formed by stacking the polarizable electrode and the current collecting electrode in a solidified state, preferably by applying pressure and heat fusing.In the case of heat fusing, a conductive adhesive layer may be formed. It is preferable to first apply a solution-type adhesive and then form an adhesive layer, as the adhesive will wet the applied surface well, but this is not limited to polyolefin resins. A mixture of the above conductive substances without a solvent or with a small amount of solvent may be melted and applied like a hot melt adhesive, and then cooled to form a bonding layer. In the case of
．． 5 parts by weight, preferably 1 to 80 parts by weight of toluene. The thickness of the conductive polyolefin resin layer is not particularly limited as long as it covers the surface of the current collecting electrode in the paper-making state.

In this way, the halogenated polyolefin resin layer is provided between the current collecting electrode and the polarizable electrode of the paper-like material, but the adhesive layer such as the current collecting electrode and the insulating material is also provided between the above-mentioned respective ones. Polarizable electrodes are stacked with a porous separator in between, and this is housed in, for example, a ring-shaped insulating material (gasket), so that the current collecting electrode has a smaller diameter than the gas get. In this case, a basic cell is completed by sealing with an electrode for external connection.

When sealing both ends of a ring-shaped insulation gasket with a current collecting electrode, it is also possible to seal this with the current collecting electrode without providing an external connection electrode.

As the external connection electrode, a metal plate, conductive rubber, imperviously treated flexible graphite, etc. can be used.

Further, the porous separator used in the present invention may be made of polymeric materials such as cellophane, polypropylene, and polyethylene, and natural fibers.

An electric double layer capacitor is completed by housing the basic cells thus produced in a single case or a combination of a plurality of cells in a case.

The electric double layer capacitor of the present invention includes not only a structure having polarizable electrodes on both sides of a porous separator and a current collecting electrode on each polarizable electrode, but also a structure in which a polarizable electrode is provided on one side of the porous separator. It also includes one in which the polarizable electrode and the porous separator are each provided with a current collecting electrode.

The conductive halogenated polyolefin resin layer formed between the current collecting electrode and the polarizable electrode of the paper-like material has excellent adhesion to dissimilar materials such as the current-collecting electrode and the polarizable electrode of the paper-like material.
Not only can the contact electrical resistance at the interface be reduced, but it is also stable in electrolytes, so it will not dissolve or swell even if it comes into contact with electrolytes at high temperatures and for long periods of time, making it suitable for use with polarizable electrodes, current collector electrodes, etc. In addition, the contact area of the fibrous conductive material entangled inside the current collecting electrode of the paper-like material increases, reducing the internal electrical resistance. can.

In addition, the organic binder can also be compressed, and compressing it increases the density of the tissue and increases the mechanical strength of the current collecting electrode itself.
You can make it that much thinner. Furthermore, for example, carbonized fibers and Manila hemp are chemically stable and are not affected by electrolytes.

〔Example〕

Next, embodiments of the present invention will be described based on FIGS. 1 to 4.

Example 1 18 parts by weight of activated carbon, 2M parts of carbon black, 5 parts by weight of 4-fufu modified tyrene resin diversion, and 60 parts by weight of ethanol were added and kneaded, and the kneaded product was molded into a sheet using a molding machine, Polarizable electrode, lt 1). 1) Prepare an electrode material (diameter 10 m, thickness 0.3 mm).

Next, as a fibrous conductive substance, PAN graphite fibers (graphitized polyacrylonitrile) with a wire diameter of 20 μm and a length of 5 mm were made using a paper machine together with an organic binder of polypropylene, and the conductive substance was organically bound. A current collecting electrode sheet (diameter 20 m) 10.10' was prepared from a paper-like material (PAN graphite fiber 80 g/rd, density 0.7 g/c+j) consisting of a paper material (PAN graphite fiber 80 g/rd, density 0.7 g/c+j) which was uniformly dispersed in the material and pressure-molded. do.

Furthermore, a polypropylene gasket 12 (outer diameter 20 m, inner diameter 15 m, thickness 0.6 n) is produced.

As shown in FIG. 1, chlorinated polypropylene ( An adhesive consisting of 1.4 parts by weight of Yamai Kokusaku Pulp ■ 1.4 parts by weight of salt removal rate (26%), 0.4 parts by weight of carbon blank, and 5.0 parts by weight of toluene was applied by a screen printing method, and the paste was heated at 70°C at 20 The adhesive layer was formed by drying for 1 minute.Next, each member, except Gasken H2, was combined in the prescribed manner and the adhesive layers were stacked, and 1) a pressure of 2 kg/- was applied at 0°C. The conductive halogenated polyolefin resin layer 1 is heated in the added state.
3. Glue each member via 13'.

A pair of capacitor members 14 thus formed.
An electrolytic solution (a 0.5 molar propylene carbonate solution of tetraethylammonium perchlorate) is injected into the polarizable electrode material 14', and the porous separator 15 made of polypropylene is impregnated with the electrolytic solution in advance. Make them face each other. Then, the gasket 12 is inserted into the periphery of the capacitor member 14.14" and then heat-sealed. As a result, the porous separator 15 is sandwiched between the polarizable electrodes 1).1)°, and the collector electrode sheets 10 on both sides thereof .10°
Thus, a basic cell sealed with the gasket 12 is completed.

Although not shown, two of the basic cells described above are stacked on a sealing container consisting of two upper and lower stainless steel members, and the ends of these upper and lower members are sealed via a polypropylene gasket to obtain an electric double layer capacitor. Ta.

This electric double layer capacitor was subjected to a high temperature load test (7
5V voltage was applied for 1000 hours at 0℃, and the internal impedance (Ω
) and capacitance were determined as follows.

That is, to measure capacitance, a sample electric double layer capacitor is connected to sample terminals 17 and 18 of the measurement circuit shown in FIG. In this state, the switch SW is connected to the terminal 19 side, and after reaching 5.5V, the voltage is switched to constant voltage charging, and the sample is charged for 30 minutes. Then switch S-
is switched to the terminal 20 side, a constant current is discharged at 5 mA as shown in FIG. Time T when it became OV,
and time T2 when the voltage becomes 2.5V. Calculate the capacitance from these measured values using the following formula.

i: Current (ip) T6, T2: Time (亦) The rate of change (%) of the capacitance thus obtained after the high load test with respect to that before the test was determined and shown in Table 1.

In addition, when measuring the internal impedance, the electric double layer capacitor of the above sample was heated at 70°C with 5.5
v, test of applying voltage for 1000 hours (high temperature load test)
A commercially available LCR meter (YHP 427
The results are shown in Table 1.

The basic cell with the structure of Example 1 has a current collecting electrode sheet, polarizable electrodes, and gasket bonded together using a conductive halogenated polyolefin resin layer, so it is conductive to both organic and aqueous electrolytes. Since the halogenated polyolefin resin layer is hard to be attacked, the interface between the polarizable electrode and the current collecting electrode sheet can maintain good contact over a long period of time.
The electrical contact resistance at the interface can be reduced. Furthermore, an electric double layer capacitor with high cell sealing properties and high reliability even at high temperatures can be obtained.

Example 2 As shown in FIG. 4, in Example 1, the chlorinated polypropylene adhesive was replaced with a chlorinated ethylene-vinyl acetate copolymer, and a carbon bra was used.

Powdered platinum was used for the wire, polyethylene was used instead of polypropylene for the paper-like collector electrode sheet, and PAN graphite wire was used instead of fibrous stainless steel with tin oxide formed on its surface. polar electrode 21
．． A conductive halogenated polyrefin resin layer 23.23'' similar to that in Example 1 was formed on the portion where the current collecting electrode sheet 20 and 20' contact each other, and the current collecting electrode and the gasket 2
An electric double layer capacitor was prepared in the same manner as in Example 1, except that a halogenated polyrefine resin layer 24.24'' not containing a conductive substance was formed between the 24. These were also measured in the same manner as in Example 1, and the results are shown in the table.

In the structure of Example 2, the gasket and the current collecting electrode sheet were bonded together using a halogenated polyolefin resin layer that did not contain a conductive substance, so there were more components contributing to adhesion than in Example 1. As a result, the adhesive strength is further increased, and the sealing performance can be improved.

Example 3 As shown in FIG. 5, a paper-like current collector electrode sheet 30.30゛ made of 6,6 nylon, AlII & fiber, both sides of a gasket 32 made of polypropylene, and a polarizable electrode 31.31゛. Stainless steel external connection electrode 34.
On each side of 34°, the chlorinated polypropylene in Example 1 was replaced with brominated polyethylene, and the carbon blank was coated with a phenolic carbon fiber reflex resin layer 33.
A basic cell was prepared in the same manner as in Example 1, except that polarizable electrodes 31.31'' were formed with angles of 35.33' and 35°, and the electrolyte in Example 1 was replaced with 30% sulfuric acid,
Six of these basic cells were stacked and sealed in the same manner as in Example 1 to produce an electric double layer capacitor. Table 1 shows the results measured in the same manner as in Example 1. This structure can also be used as a single cell.

Comparative Example A 30% sulfuric acid electrolyte, activated carbon, and carbon black were placed in a gasket ring made of butyl rubber, which was placed between a pair of unvulcanized conductive butyl rubber sheets made of carbon black powder and butyl rubber, facing each other with a porous separator in between. A basic cell was prepared by accommodating a structure in which polarizable electrodes containing the above were opposed to each other through the porous separator, and was sealed by vulcanization (Fig. 6), in the same manner as in Example 1. The measured results are shown in Table 1.

Table 1 [Effects of the Invention] According to the present invention, a halogenated polyolefin resin layer that has excellent adhesive properties and is stable in both organic and aqueous electrolytes is applied to at least the current collecting electrode and the polarizable electrode of the paper-like body. Since these are bonded together, the adhesive force is strong and can be maintained for a long period of time. Thereby, the interface between the current collecting electrode and the polarizable electrode etc. is sufficiently brought into contact with each other, and the contact electrical resistance at the interface can be reduced.

In addition, by bonding the current collecting electrode and gasket with a halogenated polyolefin resin layer, the adhesive force is high and maintained over a long period of time. A double layer condenser can be provided.

In addition, when a paper-like current collecting electrode is pressed and bonded, its contact area becomes large (and the contact due to entanglement due to internal fibers is also large, reducing the contact electrical resistance and internal resistance of the current collecting electrode). At the same time, the mechanical strength of the collector electrode can be increased by being compressed, so its thickness can be made thinner, and the thickness of the polarizable electrode can be increased accordingly, increasing the capacitance of the electric double layer capacitor. .

This makes it possible to provide an electric double layer capacitor that is thin, has a large capacity, and has a small resistance change.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an electric double layer capacitor manufactured by a manufacturing method according to an embodiment of the present invention, FIG. 2 is a measurement circuit diagram,
Fig. 3 is an explanatory diagram of its operation, Fig. 4 is a sectional view of an electric double layer capacitor of Haku's embodiment, Fig. 5 is a sectional view of an electric double layer capacitor of another embodiment, and Fig. 6 is a sectional view of a conventional electric double layer capacitor. FIG. 2 is a cross-sectional view of an electric double layer capacitor. In the figure, 1), II', 21.21', 31.31'
are polarizable electrodes, 10.10', 20.20', 3
0.30゛ is the current collecting electrode sheet, 13.13', 2
3.23', 33.33', 35.35'
1 is a conductive halogenated polyolefin resin layer, and 15 is a porous separator. February 17, 1999 Figure 2 Figure 4 5 6

Claims (5)

[Claims] (1) A non-electronically conductive and ion permeable porous separator, a polarizable electrode provided on at least one side of the porous separator, and a polarizable electrode bonded to both sides of the structure of the porous separator and polarizable electrode. In an electric double layer capacitor having a current collecting electrode and an insulating material bonded to the periphery of the current collecting electrode on both sides, the current collecting electrode is formed of a paper-like material containing at least a fibrous conductive substance and an organic binder. The current collecting electrode and at least the polarizable electrode are bonded to each other by a conductive halogen containing a halide of polyolefin resin (where halogen represents F, Cl, Br, or I) and a conductive substance. An electric double layer capacitor characterized by a layer of polyolefin-based resin. (2) The electrical terminal according to claim 1, wherein the current collecting electrode is provided with an electrode for external connection, and at least one of the current collecting electrodes and the external connection electrode are bonded to each other by a conductive halogenated polyolefin resin layer. Multilayer capacitor. (3) Insulating material on the periphery of the current collecting electrodes on both sides is made of polyolefin resin halide (however, the halogens are P, Cl, Br).
3. The electric double layer capacitor according to claim 1 or 2, wherein the electric double layer capacitor is bonded by a halogenated polyolefin resin layer containing as a main component a halogenated polyolefin resin layer. (4) The fibrous conductive substance contained in the paper-like material and the conductive substance contained in the conductive halogenated polyolefin resin layer are graphite, carbon black, carbonaceous material obtained by carbonizing a synthetic polymer, and conductive. The electric double layer capacitor according to any one of claims 1 to 3, comprising at least one of a polymer, a metal, and a metal oxide. (5) The organic binder contained in the current collecting electrode is at least one of thermoplastic resin, thermosetting resin, fluororesin, and natural fiber.
The electric double layer capacitor according to any one of claims 1 to 4, characterized in that it consists of seeds.